Preheat the oven to 350 degrees Fahnreheit. Arrange the oven racks into thirds and line two baking sheets with parchment paper. Set aside. Whisk together the flour, malted milk powder, baking soda, and salt until well blended in a medium-sized bowl.

Cream together the butter and both sugars in a stand mixer fitted with a paddle attachment at medium speed until smooth (about 1 minute). Add the hazelnut chocolate spread and mix until combined. Add the egg and the vanilla and mix until incorporated. Scrape down the sides of the bowl with a spatula, then add the flour mixture at low speed until it is just incorporated. Scrape down the sides of the bowl if necessary.

Stir in the chocolate chips and hazelnuts until evenly distributed (a couple stirs). Take tablespoons of dough and drop them onto the prepared baking sheets, spacing them out about 2 inches from each other, until the sheets are full.

Bake in the oven for 13 minutes for a softer cookie, and 15 minutes for a crisper cookie. Remove from oven and allow to cool enough to handle, then transfer them to a wire rack to finish cooling completely. Kept in an airtight container at room temperature, the cookies will keep for 2 to 3 days.